Im going on a vacation soon,
and im renting a 5d mark ii, and ditching my ol' XSi. (Well rather using it as a backup)

Its just going to be me and my girlfriend, and its an important trip to me, because im gonna be proposing to her. So I need a wireless release along with my tripod so that I can take pictures of both of us together at the national parks and all that. Since we obviously won't have anyone to take pictures of us.

My question is, do all infrared remotes made for Canon work on all Canon body's ??
I have a wireless shutter release (infrared) that works with my XSi. It also says on the website that it works with a variety of other Canon body's. But the 5d mkii isn't listed there as a compatible camera. This is the one that I own:Amazon.com: Wireless Shutter Release Remote for Canon EOS, Rebel: Camera & Photo
I know its a cheap brand remote, but I can't afford to buy all the Canon branded accessories.

Is it safe to assume that since its just infrared, that it would still work on the 5d mkii ???

Im not too worried about that. Ive used the cheap infrared on my XSi on two separate vacations and It really just worked for what I needed it to.

For the pictures of me and her, im not too worried about distance and crazy reliability, I just want to be able to take pictures of the two of us on vacation.
Im renting the 5d mkii really for landscape photos and such. Plus I really don't have the extra cash to buy something like pocketwizards, traveling from Michigan to California for 10 days + buying a ring, isn't exactly easy on the wallet. lol.

For a long time, it was only the lower level DSLR (Rebels) that has the built-in ability to trigger the shutter with a remote. My 20D certainly didn't have that ability. Someone in one of my classes asked me if the remote from their Rebel would work with their new 5DmkII and I didn't think it would...but she pulled it out and it worked. So I'm not sure which models are compatible and which aren't.

As someone that has had a Canon XS and a 5D MKII i can say taht the Cannon ir trigger works for both. the 5D MKII needs to be set on 2second or 10second timer but the IR trigger will work. I can not say for sure is the 3rd party one will but if it works on the XSI then im 95% sure it will work on the 5D MKII